package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * @author 李捷禧
 * Date: 2022/11/24
 * ClassName: RedisIdWorker
 */

@Component
public class RedisIdWorker {

    private static final long BEGIN_TIMESTAMP = 1640995200L;
    private static final int COUNT_BITS = 32;

    private StringRedisTemplate stringRedisTemplate;

    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 秒杀功能实现全局id
     * @param keyPrefix
     * @return
     */
    public long nextId(String keyPrefix){

      //1.生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long toEpochSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = toEpochSecond - BEGIN_TIMESTAMP;
        //2.生成序列号
        //生成当前日期，精确到天
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        //自增长
        long count = stringRedisTemplate.opsForValue()
                .increment("icr :" + keyPrefix + " : " + date);
        //3.拼接并返回
        return timestamp << COUNT_BITS | count;
    }

}
